Most people don't play the conspiracies because the best ones are utterly broken and might be picked even over Sol Ring and Black Lotus. The uncards can be jarring but from a power level perspective typically aren't as problematic as the top conspiracies

It depends on how deep you go. Nerf War is a one card Storm deck. Contract from Below obviously. Necro-Impotence draws you 32 cards (ie your deck after your starting hand) for 16 life. And there are a number of others that are unbalanced without being virtual insta-wins.

I'm gonna play black sheep here and state that I like this more than the black one. This fits really well in draw-go shells, the effect could be better but the opportunity cost is very low, also preventing you from drawing too many lands in lategame is "sort of" card advantage. Plays well with Sylvan Library, Top and Jace also

The opportunity cost isn't putting it in your deck. If given to me after the draft I would play this land in almost any blue deck. The opportunity cost comes from cutting a different blue card from your Cube to include a land that will rarely have an impact on the game.

maybe not at 360 but in larger list i'm pretty sure there's something to cut

I'm gonna play black sheep here and state that I like this more than the black one. This fits really well in draw-go shells, the effect could be better but the opportunity cost is very low, also preventing you from drawing too many lands in lategame is "sort of" card advantage. Plays well with Sylvan Library, Top and Jace also